Window coverings that can be opened and closed are used in a vast number of business buildings and dwellings. Examples of such coverings include horizontal blinds, vertical blinds, pleated shades, roll-up shades, and cellular shades made by, e.g., Spring Industries®, Hunter-Douglas®, Levellor®, and Somfy®. It is to be understood that while the remote control of window coverings is envisioned and used as one exemplary application, the principles set forth herein may be applied to other systems, including, without limitation, awnings, security screens, projection screens, lighting systems and controls, battery operated radios, televisions, and stereos, and the like wherein conservation of battery power is desired.
Several effective systems for advantageously either lowering or raising a window covering, or for moving the slats of a window covering between open and closed positions, have been provided. Such systems are disclosed in U.S. Pat. Nos. 6,189,592, 5,495,153, and 5,907,227, incorporated herein by reference. These systems include a motor driven gear box that is coupled to a tilt rod or roller tube of the window covering. When the motor is energized, the tilt rod (or roller tube) rotates clockwise or counterclockwise. These systems can be, e.g., operated via a remote control unit. Typically, these remotely operated systems include an infrared (IR) transmitter in the remote control unit and an IR receiver in an actuator that is mechanically coupled to the blinds. In most cases, the receiver remains awake constantly or pulses between on and off. Thus, when a signal is sent by the transmitter, the receiver can receive it, but in the case of pulsed receivers, only when the receiver is in the “on” state. The receiver can require a relatively high amount of current in order to properly operate. As a result, if the receiver is powered by a direct current power source such as a battery it can quickly drain the battery. On the other hand, continuously pulsing the receiver between power on and power off can help increase battery life, but the battery still can relatively quickly lose power, since the duty cycle between “off” and “on” must be relatively short, to avoid missing a user signal. Even then, unacceptable delay can exist from when a user toggles a control button on the remote and the window covering starts to move.
Accordingly, the present invention recognizes a need for a control system for a motorized window covering that further conserves power, and that has a short response time.